A transmission electron microscope, in addition to its evacuated housing and the electron beam generator thereof, includes a system for forming an electron beam image of the object, article or material which is subjected to the electron beam microscope and for outputting the electron image. In addition, the transmission electron microscope can include a luminescent screen which can be inserted into the electron beam path for transforming the electron image into a photon image, an optical element for rerouting the photon image through a right angle to the electron beam, and a camera which can be connected to the optical element by an optical lens system so that the camera can register optically the photon image corresponding to the electron image.
In a camera system of this type (see U.S. Pat. No. 5,517,033) the optical lens system in the camera are rigid with the projection chamber and only the luminescent screen and the rerouting optical device need be movable within the projection chamber. While this does give rise to a very simple mechanical system, it has the drawback that positioning of the luminescent screen and the rerouting element relative to the lens optics and the camera cannot be reproducible to less than a fraction of a millimeter and thus the camera system cannot be used for high resolution image formation.
In another camera system for an electron transmission microscope, the luminescent screen is connected with a CCD camera by a fiber optics system (U.S. Pat. No. 4,739,399). Here the luminescent screen, the fiber optics and the CCD camera are provided as a single rigid structural unit within the projection camera and both the luminescent screen and the CCD camera directly adjoin the optical fiber ends. The drawback of this system is that the image sensor of the CCD camera must have the same size as the luminescent screen and thus is prohibitively expensive.